Pipelines, such as oil and gas pipelines, often need to be anchored or otherwise stabilized. For example, underwater pipelines and pipelines buried near or in saturated soils are buoyant and, thus, have a tendency to float. To prevent damage to the pipes and, thus, prevent a potential catastrophic leak of the material within the pipe, this buoyancy must be controlled. A variety of assemblies and methods are known for anchoring such pipelines. More particularly, passive gravity systems, such as weights, are common. Other known systems employ helical screw anchors with steel or polyester pipebands.
A representative example of a conventional pipeline anchor apparatus is disclosed in U.S. Pat. No. 5,730,552 (“the '552 patent”) to Johannesson et al. The '552 patent discloses a pipeline anchor apparatus with left and right anchor units connected by a tie-down strap made of heavy-duty polyester or nylon webbing. Two respective tie-down brackets located on opposite sides of the pipe hold a respective end of the strap, which is placed over the top of the pipe. The brackets are attached to extension rods which are coupled to anchor rods that are driven into the ground. The tie-down brackets pivot about the extension rods to reduce stress placed on the pipe as the pipe shifts, for example, due to buoyancy forces.
The polyester tie-down strap of the '552 patent has a loop formed and sewn at each of its opposite ends. Each loop is secured to a tie-down bracket along a side thereof facing the pipeline. The tie-down brackets are mounted to extension rods which, in turn, are attached to anchor rods of the respective anchor units. Each anchor rod has a helical anchor attached thereabout. Further, each tie-down bracket has a side sleeve-like connector defining a channel or slot running alongside the bracket through which passes one of the tie-down strap loops. Each loop of the tie-down strap wraps around an outer wall of the side connector of one of the tie-down brackets.
Another representative example of previously known pipeline anchor apparatuses is disclosed in U.S. Pat. No. 6,132,141 (the '141 patent), to Kirk. The '141 patent discloses a pipeline retainer device having a pair of tie-down attachment members mounted to helical screw anchor rods. The attachment members are connected to opposite portions of a strap that holds the pipeline down. A retainer body comprising an annular shoulder portion attached to each hollow tubular mounting body distributes stress caused by shifting of the pipe at the ends of the strap.
An even further representative example of previously known pipeline anchor apparatuses is disclosed in U.S. Pat. No. 4,338,045 (the '045 patent), to Cour. Specifically, the '045 patent discloses a method and apparatus for anchoring a pipeline to a support and a sea-bed. An inflatable body is placed on the upper portion of the pipeline and a rigid saddle clamp is placed over the inflatable body and the pipe, which is coated with concrete. The ends of the saddle clamp are attached to anchors driven into the ground and the inflatable body is then filled with a settable material, such as concrete. Once the settable material has settled, any play between the pipe and the saddle clamp, particularly in the vertical direction, is removed.
None of the previously known devices and methods for retaining a buoyant pipeline, including the U.S. patents mentioned above, sufficiently account for vertical stresses exerted on the various respective tie-down straps or retainers. As a result, broken or otherwise damaged retainers and straps could result when previously known pipeline anchoring systems, such as those mentioned above, are used. Furthermore, previously known pipeline anchoring systems such as those identified above are configured to retain a single pipeline. None of the aforementioned pipeline retention systems is designed to accommodate more than one respective pipeline simultaneously.
There remains a need, therefore, for a pipeline anchoring device that addresses the aforesaid problems, and others, attendant with conventional and other previously known pipeline anchor devices and which is also easily manufactured and installed.